Adjustable lift fork mounting



" ited tates ADJUSTABLE LIFT FORK MOUNTING Filed June 25, 1959, Ser. No. 822,795

3 Clairns. (Cl. 214-731) This invention relates to industrial -trucks and more particularly to a looking means for the transversely adjustable lift forks commonly used on such truoks. It is often desirable to adjustably and detachably mount the lift forks on 'the hoist carriage of an industrial truck to provide different spaoings or to provide a single fork or a number of sp'aced forks of the proper size and shape to meet the requirements of the particular materials being handled.

The looking means of the present invention is applicable to forks having a hook type mounting in which the Vertical supporting leg of each fork has rearwardly projeoting hook shaped lugs that engage With upper and lower horizontal guide ribs each formed on a bar or plate attached to the lift carriage.

In order to facilitate removal and adjustment, the upper and lower guide lugs of the forks are spaced apart a distance slightly greater than the spacing of the guide ribs to provide the olearance necessary for easy adjustment. The load is imposed upon the upper lug of the fork which has a downwardly projecting inner end portion spaced from the rear face of the fork leg to receive the upper guide rib.

For securing the forks in adjusted positions, a vertically disposed looking pin is slidably mounted in the upper lug of the fork and axial movement into and out of the rib receiving reoess. The looking pin is engageable with any one of a series of longitudinally spaced looking recesses in the upper guide rib.

The looking device of the present invention is provided with a simple and easily releasable means for positively holding the looking pin against axial movement, either in its looking position where it holds the fork against lateral movement or in its releasing position where it perrnits free lateral sliding movement of the fork on the guide rib.

.Objects of the invention are to provide a pin retaning means that is easily releasable to permit ax-ial shifting of the pin from its looking to its releasing position and vice versa, to provide a retainer that is positioned wholly withinv the pin sockets of the fork so that it is protected against damage by impacts and that is moved into and out of pin retaining position by turning movements of the pin.

Reference should be had to the accompanying drawings forming a part of this specification, in which:

Figure 1 is a fragmentary side elevation of the forward end of an industrial truck provided with a lift carriage and load carrying fork;

Fig. 2 is a fragmentary front elevation viewed as indicated at 2 2 in Fig. l, showing the upper guide and a pair of lift forks supported thereon;

Fig. 3 is a fragmentary side elevation partially in vertical section showing the means for looking a fork in an adjusted position;

Fig. 4 is a view similar to Fig. 3 showing the fork only with -the looking pin in retracted position;

i Patented Mar. 21, 1951 Fg.'5 is a section taken on the line ndioated at 5-5 in Fig. 3; and

Fig. 6 is a perspective view of the pin guiding sleeve.

Referring to the accompanying drawings, Fig. l shows the forward end of an industrial truck 1 upon which is mounted one or more lift forks 2 that are attached to a carriage 3 mounted for Vertical travel on a standard 4 at the forward end of the truck. The lift forks 2 may be of conventional construction each provided with a Vertical 'attaching leg 5 and a horizontal load supporting leg 6. The Vertical leg of each fork is adjustably mounted on the oarriage 3 by means of upper and lower horizontal guides '7 and 8 which may be formed on the top and bottom edges of a single plate or on spaced bars or plates. The upper guide 7 is formed to provide an upwardly projecting longitudinal rib 9 the front face of which is flush with the front face of the bar or plate forming the upper guide. The rib 9 has a downwardly and rearwardly inclined rear face 10 and the guide plate or bar has a horizontal top face 11 inwardly of the rib 9. The upper end of the attaching leg 5 of the fork has a rearwardly projecting hook-shaped portion 12 and a downwardly projeoting portion 13 spaced from the rear face of the leg 5 to provide a rib receiving recess 14 that is of a depth greater than the height of the rib 9 and of a width greater than the thickness of the rib 9. As herein shown, the downwardly projecting portion 13 has an inclined face 15 that conforms to the inclined rear face 10 of the rib 9, the downwardly projecting portion 13 also having a horizontal end face 16 that engages the horizontal top face of the guide 7.

The lower guide 8 may be identioal with the upper guide 7 except that its position is reveised, having a downwardly extending rib 17 corresponding to the rib 9 of the upper guide. The attaching leg 5 of the fork has a lower hook-shaped lug 18 reversely positioned With respect to the upper |hook 12, being provided with an upwardly projeotng portion 19 that corresponds to the downwardly projecting portion 13 of lthe upper hook and that is spaced from the rear face of the leg 5 to provide a recess to receive the lower guide rib 17.

The rearwardly projecting portion 12 of the attaching leg 5 is provided with a Vertical bore 20 opening to the upper end of its recess 14 and has a counterbore 21 coaxial with -the bore 20 and extending to the top face of the hook portion 12. A looking pin 22 is mounted for Vertical sliding movement in the socket formed by the bore 20 'and counterbore 21, having a reduced portion 23 that fits in the bore 20 and a shoulder 24 at the upper end of the reduced portion 23 that is engageable with the bottom of the counterbore 21 to limit the downward movement of the looking pin 22. The pin 22 projects above the top face of the hook portion 12 and is provided with an enlarged head 25 at its upper end that provides a oonvenient grip and that may be knurled to facilitate turning. Means is provided within the pin lreceiving socket of the fork for retaining the looking pin 22 either in its looking or its retraoted position, the retaining means being Controlled by turning movements of the pin. As herein shown the looking pin 22 is of a diameter less than that of the counterbore 21 land is guided by means of a resilient contractible sleeve 26 mounted in the counterbore 21. The sleeve 26 has a longitudinal split 27 which permits the sleeve yto be contracted sufliciently to vpermit it to be entered into the counterbore 21 in which the sleeve is seourely held by its expanding thrust on the wall of the counterbore. The sleeve has a Vertical slot 28 intermediate its ends that is provided with upper and lower lateral extensions 29 and 30. A pin retaining means 'is provided that moves axially with the pin 22 and that also turns With the pin 22 and that engages in the lateral extension 29 to retain the pin in retracted position and in the lateral extension 30 to retain the pin in looking position. As herein shown the looking pin V22 is provided with a recess 31 that may be formed by cutting a transverse V-shaped notch .of a depth to accommodate ,a retaining member in the form of a spherical metal ball 32 between the walls of the notch and the nterior of the counterbore 21. The width of the slot 28 is greater than the diameter of the ball 32, so that the ball, which is constrained by the recess 31 to move axially and angularly with the pin, can move vertically with the pin 22 or lateraily into the end portions 29 or 30 of the slot by imparting a turning movement to the pin. The laterally extend'ing end portions 29 and 30 provide means for retaining the pin 2-2 in its uppermost or lowermost position so that, to move the pin to its retracted position, the pin may be turned by means of the knurled head 25 to move the ball into al'inement with the Vertical portion 28 of lthe slot, which permits the pin to be lifted to its retracted position and retained in its `retracted position by turn'lng the pin to move the ball into the upper lateral extension 29 of the slot.

The upper guide rib 9 may be provided with a series of looking recesses in the form of notches 33 of identical width that ex'tend across the ribs and that have parallel side walls 34 spaced apart a dist'ance corresponding to the diameter of the reduced portion 23 of the looking pin. The pin receiving notches may be distributed in any suitable manner along the length of the guide r-ib 9. As herein shown a group of closely spaced notches 33 are provided adjacent each end of the rib to permit adjustment of the spacing of the forks. It is sometimes desirable to provide a single load carrying book, in which case the hook should be mounted centrally of the supporting carriage 3. To enable a single hook to be centrally mounted, the rib 9 may be provided with a central pin receiving notch 33a and pin receiving notches 3312 may be positioned on opposite sides of the notch 33a to enable two forks to he mounted side by side in abutting relation centrally of the carriage 3.

It is to be understood that in accordance with the provisions of the patent statutes, variations and modifications of the specfic devices herein shown and described may be made without departing from the spirit of the invention.

What I claim is:

l. In an adjustable mounting for lift forks of the type in which a carriage is provided with a horizontally extending upwardly projecting guide rib that has longit-udinally spaced upwardly opening looking recesses, in which a lift fork is provided with an upright attaching leg that has an enlarged upper e'nd shaped to provide a top face and la rearwardly projecting hook portion provided with a downwardly opening recess beneath said top face that receives said rib, and in which said hook portion has a bore opening to said rib receiving recess and a counterbore opening to said -top face and to said bore, fork locking means comprising an intern-ally cylindrical bearing sleeve positioned in said counterbore and fit'ting within the same, said sleeve having a vertically extendng slot with vertically spaced circumferentially extending portions within the counterbore, a locking pin slidably and rotatably fitting in said sleeve, said pin being movable downwardly to a fork looking position in which its lower end engages in -a locking recess of said guide rib and upwardly to a fork releasing position Where its lower end is above and clear of said rib, the upper end of said pin project'ing above the top face of said leg and providing a hand grip for lifting and turning said pin, and a retaining member movable axially and angularly with said pin, said re'taining member project'ing into said slot and movable vertioally with the pin from one circumferentially extending portion thereof to the other and angularly With the pin into either circumferentially extending portion, said ci'rcumferentally extending por-tion of the slot provid-ing upper and lower Shoulders for retaining the pin in lan upper position clear of the rib or in a lower position where it engages in a looking recess of the rib.

2. A lift fork looking means according vto claim l in which the bearing sleeve is formed of resilient metal, is normally of an external diameter greater than the internal diameter of the counterbore in which it is mounted and is longitudinally split so that it c-an be compressed to a smaller diameter for insertion into said counterbore and will exent an expanding thrust upon the wall of the counterbore to hold it in place.

3. A lift fork looking means according to claim 1 in which the retaining member movable with the looking pin is in the form of a ball of a diameter greater than the thickness of the sleeve and in which the ball is 'connected to the pin to move axially and angularly therewith by means of a notch in the pin into which Vthe ball extends and in which the ball lis retained by the wall of the counterbore.

References Cited in the file of this patent UNITED STATES PATENTS 258,997 Crandal June 6, 1882 7,568,689 Nystrom Jan. 5, 1926 2,847,138 Backofen et al Aug. 12, 1958 FOREIGN PATENTS 203,789 Great Britain Sept. 14, 1923 

